Add support for numpy arrays (and dicts) to approx.

This fixes #1994.  It turned out to require a lot of refactoring because
subclassing numpy.ndarray was necessary to coerce python into calling
the right `__eq__` operator.
This commit is contained in:
Kale Kundert 2017-06-11 19:27:41 -07:00
parent 467c526307
commit 9f3122fec6
No known key found for this signature in database
GPG Key ID: C6238221D17CAFAE
2 changed files with 408 additions and 171 deletions

View File

@ -1117,7 +1117,6 @@ def raises(expected_exception, *args, **kwargs):
...
Failed: Expecting ZeroDivisionError
.. note::
When using ``pytest.raises`` as a context manager, it's worthwhile to
@ -1150,7 +1149,6 @@ def raises(expected_exception, *args, **kwargs):
>>> with raises(ValueError, match=r'must be \d+$'):
... raise ValueError("value must be 42")
Or you can specify a callable by passing a to-be-called lambda::
>>> raises(ZeroDivisionError, lambda: 1/0)
@ -1230,10 +1228,8 @@ def raises(expected_exception, *args, **kwargs):
return _pytest._code.ExceptionInfo()
fail(message)
raises.Exception = fail.Exception
class RaisesContext(object):
def __init__(self, expected_exception, message, match_expr):
self.expected_exception = expected_exception
@ -1265,9 +1261,271 @@ class RaisesContext(object):
return suppress_exception
# builtin pytest.approx helper
class approx(object):
class ApproxBase(object):
"""
Provide shared utilities for making approximate comparisons between numbers
or sequences of numbers.
"""
def __init__(self, expected, rel=None, abs=None):
self.expected = expected
self.abs = abs
self.rel = rel
def __repr__(self):
return ', '.join(
repr(self._approx_scalar(x))
for x in self._yield_expected())
def __eq__(self, actual):
return all(
a == self._approx_scalar(x)
for a, x in self._yield_comparisons(actual))
__hash__ = None
def __ne__(self, actual):
return not (actual == self)
def _approx_scalar(self, x):
return ApproxScalar(x, rel=self.rel, abs=self.abs)
def _yield_expected(self, actual):
"""
Yield all the expected values associated with this object. This is
used to implement the `__repr__` method.
"""
raise NotImplementedError
def _yield_comparisons(self, actual):
"""
Yield all the pairs of numbers to be compared. This is used to
implement the `__eq__` method.
"""
raise NotImplementedError
try:
import numpy as np
class ApproxNumpy(ApproxBase, np.ndarray):
"""
Perform approximate comparisons for numpy arrays.
This class must inherit from numpy.ndarray in order to allow the approx
to be on either side of the `==` operator. The reason for this has to
do with how python decides whether to call `a.__eq__()` or `b.__eq__()`
when it encounters `a == b`.
If `a` and `b` are not related by inheritance, `a` gets priority. So
as long as `a.__eq__` is defined, it will be called. Because most
implementations of `a.__eq__` end up calling `b.__eq__`, this detail
usually doesn't matter. However, `numpy.ndarray.__eq__` raises an
error complaining that "the truth value of an array with more than
one element is ambiguous. Use a.any() or a.all()" when compared with a
custom class, so `b.__eq__` never gets called.
The trick is that the priority rules change if `a` and `b` are related
by inheritance. Specifically, `b.__eq__` gets priority if `b` is a
subclass of `a`. So we can guarantee that `ApproxNumpy.__eq__` gets
called by inheriting from `numpy.ndarray`.
"""
def __new__(cls, expected, rel=None, abs=None):
"""
Numpy uses __new__ (rather than __init__) to initialize objects.
The `expected` argument must be a numpy array. This should be
ensured by the approx() delegator function.
"""
assert isinstance(expected, np.ndarray)
obj = super(ApproxNumpy, cls).__new__(cls, expected.shape)
obj.__init__(expected, rel, abs)
return obj
def __repr__(self):
# It might be nice to rewrite this function to account for the
# shape of the array...
return '[' + ApproxBase.__repr__(self) + ']'
def __eq__(self, actual):
try:
actual = np.array(actual)
except:
raise ValueError("cannot cast '{0}' to numpy.ndarray".format(actual))
if actual.shape != self.expected.shape:
return False
return ApproxBase.__eq__(self, actual)
def _yield_expected(self):
for x in self.expected:
yield x
def _yield_comparisons(self, actual):
# We can be sure that `actual` is a numpy array, because it's
# casted in `__eq__` before being passed to `ApproxBase.__eq__`,
# which is the only method that calls this one.
for i in np.ndindex(self.expected.shape):
yield actual[i], self.expected[i]
except ImportError:
np = None
class ApproxMapping(ApproxBase):
"""
Perform approximate comparisons for mappings where the values are numbers
(the keys can be anything).
"""
def __repr__(self):
item = lambda k, v: "'{0}': {1}".format(k, self._approx_scalar(v))
return '{' + ', '.join(item(k,v) for k,v in self.expected.items()) + '}'
def __eq__(self, actual):
if actual.keys() != self.expected.keys():
return False
return ApproxBase.__eq__(self, actual)
def _yield_comparisons(self, actual):
for k in self.expected.keys():
yield actual[k], self.expected[k]
class ApproxSequence(ApproxBase):
"""
Perform approximate comparisons for sequences of numbers.
"""
def __repr__(self):
open, close = '()' if isinstance(self.expected, tuple) else '[]'
return open + ApproxBase.__repr__(self) + close
def __eq__(self, actual):
if len(actual) != len(self.expected):
return False
return ApproxBase.__eq__(self, actual)
def _yield_expected(self):
return iter(self.expected)
def _yield_comparisons(self, actual):
return zip(actual, self.expected)
class ApproxScalar(ApproxBase):
"""
Perform approximate comparisons for single numbers only.
"""
def __repr__(self):
"""
Return a string communicating both the expected value and the tolerance
for the comparison being made, e.g. '1.0 +- 1e-6'. Use the unicode
plus/minus symbol if this is python3 (it's too hard to get right for
python2).
"""
if isinstance(self.expected, complex):
return str(self.expected)
# Infinities aren't compared using tolerances, so don't show a
# tolerance.
if math.isinf(self.expected):
return str(self.expected)
# If a sensible tolerance can't be calculated, self.tolerance will
# raise a ValueError. In this case, display '???'.
try:
vetted_tolerance = '{:.1e}'.format(self.tolerance)
except ValueError:
vetted_tolerance = '???'
if sys.version_info[0] == 2:
return '{0} +- {1}'.format(self.expected, vetted_tolerance)
else:
return u'{0} \u00b1 {1}'.format(self.expected, vetted_tolerance)
def __eq__(self, actual):
"""
Return true if the given value is equal to the expected value within
the pre-specified tolerance.
"""
from numbers import Number
# Give a good error message we get values to compare that aren't
# numbers, rather than choking on them later on.
if not isinstance(actual, Number):
raise ValueError("approx can only compare numbers, not '{0}'".format(actual))
if not isinstance(self.expected, Number):
raise ValueError("approx can only compare numbers, not '{0}'".format(self.expected))
# Short-circuit exact equality.
if actual == self.expected:
return True
# Infinity shouldn't be approximately equal to anything but itself, but
# if there's a relative tolerance, it will be infinite and infinity
# will seem approximately equal to everything. The equal-to-itself
# case would have been short circuited above, so here we can just
# return false if the expected value is infinite. The abs() call is
# for compatibility with complex numbers.
if math.isinf(abs(self.expected)):
return False
# Return true if the two numbers are within the tolerance.
return abs(self.expected - actual) <= self.tolerance
__hash__ = None
@property
def tolerance(self):
"""
Return the tolerance for the comparison. This could be either an
absolute tolerance or a relative tolerance, depending on what the user
specified or which would be larger.
"""
set_default = lambda x, default: x if x is not None else default
# Figure out what the absolute tolerance should be. ``self.abs`` is
# either None or a value specified by the user.
absolute_tolerance = set_default(self.abs, 1e-12)
if absolute_tolerance < 0:
raise ValueError("absolute tolerance can't be negative: {}".format(absolute_tolerance))
if math.isnan(absolute_tolerance):
raise ValueError("absolute tolerance can't be NaN.")
# If the user specified an absolute tolerance but not a relative one,
# just return the absolute tolerance.
if self.rel is None:
if self.abs is not None:
return absolute_tolerance
# Figure out what the relative tolerance should be. ``self.rel`` is
# either None or a value specified by the user. This is done after
# we've made sure the user didn't ask for an absolute tolerance only,
# because we don't want to raise errors about the relative tolerance if
# we aren't even going to use it.
relative_tolerance = set_default(self.rel, 1e-6) * abs(self.expected)
if relative_tolerance < 0:
raise ValueError("relative tolerance can't be negative: {}".format(absolute_tolerance))
if math.isnan(relative_tolerance):
raise ValueError("relative tolerance can't be NaN.")
# Return the larger of the relative and absolute tolerances.
return max(relative_tolerance, absolute_tolerance)
def approx(expected, rel=None, abs=None):
"""
Assert that two numbers (or two sets of numbers) are equal to each other
within some tolerance.
@ -1307,6 +1565,8 @@ class approx(object):
>>> (0.1 + 0.2, 0.2 + 0.4) == approx((0.3, 0.6))
True
>>> {'a': 0.1 + 0.2, 'b': 0.2 + 0.4} == approx({'a': 0.3, 'b': 0.6})
True
By default, ``approx`` considers numbers within a relative tolerance of
``1e-6`` (i.e. one part in a million) of its expected value to be equal.
@ -1380,139 +1640,37 @@ class approx(object):
special case that you explicitly specify an absolute tolerance but not a
relative tolerance, only the absolute tolerance is considered.
"""
from collections import Mapping, Sequence
try:
String = basestring # python2
except NameError:
String = str, bytes # python3
def __init__(self, expected, rel=None, abs=None):
self.expected = expected
self.abs = abs
self.rel = rel
# Delegate the comparison to a class that knows how to deal with the type
# of the expected value (e.g. int, float, list, dict, numpy.array, etc).
#
# This architecture is really driven by the need to support numpy arrays.
# The only way to override `==` for arrays without requiring that approx be
# the left operand is to inherit the approx object from `numpy.ndarray`.
# But that can't be a general solution, because it requires (1) numpy to be
# installed and (2) the expected value to be a numpy array. So the general
# solution is to delegate each type of expected value to a different class.
#
# This has the advantage that it made it easy to support mapping types
# (i.e. dict). The old code accepted mapping types, but would only compare
# their keys, which is probably not what most people would expect.
def __repr__(self):
return ', '.join(repr(x) for x in self.expected)
if np and isinstance(expected, np.ndarray):
cls = ApproxNumpy
elif isinstance(expected, Mapping):
cls = ApproxMapping
elif isinstance(expected, Sequence) and not isinstance(expected, String):
cls = ApproxSequence
else:
cls = ApproxScalar
def __eq__(self, actual):
from collections import Iterable
if not isinstance(actual, Iterable):
actual = [actual]
if len(actual) != len(self.expected):
return False
return all(a == x for a, x in zip(actual, self.expected))
__hash__ = None
def __ne__(self, actual):
return not (actual == self)
@property
def expected(self):
# Regardless of whether the user-specified expected value is a number
# or a sequence of numbers, return a list of ApproxNotIterable objects
# that can be compared against.
from collections import Iterable
approx_non_iter = lambda x: ApproxNonIterable(x, self.rel, self.abs)
if isinstance(self._expected, Iterable):
return [approx_non_iter(x) for x in self._expected]
else:
return [approx_non_iter(self._expected)]
@expected.setter
def expected(self, expected):
self._expected = expected
class ApproxNonIterable(object):
"""
Perform approximate comparisons for single numbers only.
In other words, the ``expected`` attribute for objects of this class must
be some sort of number. This is in contrast to the ``approx`` class, where
the ``expected`` attribute can either be a number of a sequence of numbers.
This class is responsible for making comparisons, while ``approx`` is
responsible for abstracting the difference between numbers and sequences of
numbers. Although this class can stand on its own, it's only meant to be
used within ``approx``.
"""
def __init__(self, expected, rel=None, abs=None):
self.expected = expected
self.abs = abs
self.rel = rel
def __repr__(self):
if isinstance(self.expected, complex):
return str(self.expected)
# Infinities aren't compared using tolerances, so don't show a
# tolerance.
if math.isinf(self.expected):
return str(self.expected)
# If a sensible tolerance can't be calculated, self.tolerance will
# raise a ValueError. In this case, display '???'.
try:
vetted_tolerance = '{:.1e}'.format(self.tolerance)
except ValueError:
vetted_tolerance = '???'
if sys.version_info[0] == 2:
return '{0} +- {1}'.format(self.expected, vetted_tolerance)
else:
return u'{0} \u00b1 {1}'.format(self.expected, vetted_tolerance)
def __eq__(self, actual):
# Short-circuit exact equality.
if actual == self.expected:
return True
# Infinity shouldn't be approximately equal to anything but itself, but
# if there's a relative tolerance, it will be infinite and infinity
# will seem approximately equal to everything. The equal-to-itself
# case would have been short circuited above, so here we can just
# return false if the expected value is infinite. The abs() call is
# for compatibility with complex numbers.
if math.isinf(abs(self.expected)):
return False
# Return true if the two numbers are within the tolerance.
return abs(self.expected - actual) <= self.tolerance
__hash__ = None
def __ne__(self, actual):
return not (actual == self)
@property
def tolerance(self):
set_default = lambda x, default: x if x is not None else default
# Figure out what the absolute tolerance should be. ``self.abs`` is
# either None or a value specified by the user.
absolute_tolerance = set_default(self.abs, 1e-12)
if absolute_tolerance < 0:
raise ValueError("absolute tolerance can't be negative: {}".format(absolute_tolerance))
if math.isnan(absolute_tolerance):
raise ValueError("absolute tolerance can't be NaN.")
# If the user specified an absolute tolerance but not a relative one,
# just return the absolute tolerance.
if self.rel is None:
if self.abs is not None:
return absolute_tolerance
# Figure out what the relative tolerance should be. ``self.rel`` is
# either None or a value specified by the user. This is done after
# we've made sure the user didn't ask for an absolute tolerance only,
# because we don't want to raise errors about the relative tolerance if
# we aren't even going to use it.
relative_tolerance = set_default(self.rel, 1e-6) * abs(self.expected)
if relative_tolerance < 0:
raise ValueError("relative tolerance can't be negative: {}".format(absolute_tolerance))
if math.isnan(relative_tolerance):
raise ValueError("relative tolerance can't be NaN.")
# Return the larger of the relative and absolute tolerances.
return max(relative_tolerance, absolute_tolerance)
return cls(expected, rel, abs)
#

View File

@ -9,7 +9,6 @@ from decimal import Decimal
from fractions import Fraction
inf, nan = float('inf'), float('nan')
class MyDocTestRunner(doctest.DocTestRunner):
def __init__(self):
@ -29,12 +28,19 @@ class TestApprox(object):
if sys.version_info[:2] == (2, 6):
tol1, tol2, infr = '???', '???', '???'
assert repr(approx(1.0)) == '1.0 {pm} {tol1}'.format(pm=plus_minus, tol1=tol1)
assert repr(approx([1.0, 2.0])) == '1.0 {pm} {tol1}, 2.0 {pm} {tol2}'.format(pm=plus_minus, tol1=tol1, tol2=tol2)
assert repr(approx([1.0, 2.0])) == '[1.0 {pm} {tol1}, 2.0 {pm} {tol2}]'.format(pm=plus_minus, tol1=tol1, tol2=tol2)
assert repr(approx((1.0, 2.0))) == '(1.0 {pm} {tol1}, 2.0 {pm} {tol2})'.format(pm=plus_minus, tol1=tol1, tol2=tol2)
assert repr(approx(inf)) == 'inf'
assert repr(approx(1.0, rel=nan)) == '1.0 {pm} ???'.format(pm=plus_minus)
assert repr(approx(1.0, rel=inf)) == '1.0 {pm} {infr}'.format(pm=plus_minus, infr=infr)
assert repr(approx(1.0j, rel=inf)) == '1j'
# Dictionaries aren't ordered, so we need to check both orders.
assert repr(approx({'a': 1.0, 'b': 2.0})) in (
"{{'a': 1.0 {pm} {tol1}, 'b': 2.0 {pm} {tol2}}}".format(pm=plus_minus, tol1=tol1, tol2=tol2),
"{{'b': 2.0 {pm} {tol2}, 'a': 1.0 {pm} {tol1}}}".format(pm=plus_minus, tol1=tol1, tol2=tol2),
)
def test_operator_overloading(self):
assert 1 == approx(1, rel=1e-6, abs=1e-12)
assert not (1 != approx(1, rel=1e-6, abs=1e-12))
@ -228,18 +234,38 @@ class TestApprox(object):
# tolerance, so only an absolute tolerance is calculated.
assert a != approx(x, abs=inf)
def test_expecting_sequence(self):
within_1e8 = [
(1e8 + 1e0, 1e8),
(1e0 + 1e-8, 1e0),
(1e-8 + 1e-16, 1e-8),
def test_int(self):
within_1e6 = [
(1000001, 1000000),
(-1000001, -1000000),
]
actual, expected = zip(*within_1e8)
assert actual == approx(expected, rel=5e-8, abs=0.0)
for a, x in within_1e6:
assert a == approx(x, rel=5e-6, abs=0)
assert a != approx(x, rel=5e-7, abs=0)
assert approx(x, rel=5e-6, abs=0) == a
assert approx(x, rel=5e-7, abs=0) != a
def test_expecting_sequence_wrong_len(self):
assert [1, 2] != approx([1])
assert [1, 2] != approx([1,2,3])
def test_decimal(self):
within_1e6 = [
(Decimal('1.000001'), Decimal('1.0')),
(Decimal('-1.000001'), Decimal('-1.0')),
]
for a, x in within_1e6:
assert a == approx(x, rel=Decimal('5e-6'), abs=0)
assert a != approx(x, rel=Decimal('5e-7'), abs=0)
assert approx(x, rel=Decimal('5e-6'), abs=0) == a
assert approx(x, rel=Decimal('5e-7'), abs=0) != a
def test_fraction(self):
within_1e6 = [
(1 + Fraction(1, 1000000), Fraction(1)),
(-1 - Fraction(-1, 1000000), Fraction(-1)),
]
for a, x in within_1e6:
assert a == approx(x, rel=5e-6, abs=0)
assert a != approx(x, rel=5e-7, abs=0)
assert approx(x, rel=5e-6, abs=0) == a
assert approx(x, rel=5e-7, abs=0) != a
def test_complex(self):
within_1e6 = [
@ -251,33 +277,86 @@ class TestApprox(object):
for a, x in within_1e6:
assert a == approx(x, rel=5e-6, abs=0)
assert a != approx(x, rel=5e-7, abs=0)
assert approx(x, rel=5e-6, abs=0) == a
assert approx(x, rel=5e-7, abs=0) != a
def test_int(self):
within_1e6 = [
(1000001, 1000000),
(-1000001, -1000000),
]
for a, x in within_1e6:
assert a == approx(x, rel=5e-6, abs=0)
assert a != approx(x, rel=5e-7, abs=0)
def test_list(self):
actual = [1 + 1e-7, 2 + 1e-8]
expected = [1, 2]
def test_decimal(self):
within_1e6 = [
(Decimal('1.000001'), Decimal('1.0')),
(Decimal('-1.000001'), Decimal('-1.0')),
]
for a, x in within_1e6:
assert a == approx(x, rel=Decimal('5e-6'), abs=0)
assert a != approx(x, rel=Decimal('5e-7'), abs=0)
# Return false if any element is outside the tolerance.
assert actual == approx(expected, rel=5e-7, abs=0)
assert actual != approx(expected, rel=5e-8, abs=0)
assert approx(expected, rel=5e-7, abs=0) == actual
assert approx(expected, rel=5e-8, abs=0) != actual
def test_fraction(self):
within_1e6 = [
(1 + Fraction(1, 1000000), Fraction(1)),
(-1 - Fraction(-1, 1000000), Fraction(-1)),
]
for a, x in within_1e6:
assert a == approx(x, rel=5e-6, abs=0)
assert a != approx(x, rel=5e-7, abs=0)
def test_list_wrong_len(self):
assert [1, 2] != approx([1])
assert [1, 2] != approx([1,2,3])
def test_tuple(self):
actual = (1 + 1e-7, 2 + 1e-8)
expected = (1, 2)
# Return false if any element is outside the tolerance.
assert actual == approx(expected, rel=5e-7, abs=0)
assert actual != approx(expected, rel=5e-8, abs=0)
assert approx(expected, rel=5e-7, abs=0) == actual
assert approx(expected, rel=5e-8, abs=0) != actual
def test_tuple_wrong_len(self):
assert (1, 2) != approx((1,))
assert (1, 2) != approx((1,2,3))
def test_dict(self):
actual = {'a': 1 + 1e-7, 'b': 2 + 1e-8}
expected = {'b': 2, 'a': 1} # Dictionaries became ordered in python3.6,
# so make sure the order doesn't matter
# Return false if any element is outside the tolerance.
assert actual == approx(expected, rel=5e-7, abs=0)
assert actual != approx(expected, rel=5e-8, abs=0)
assert approx(expected, rel=5e-7, abs=0) == actual
assert approx(expected, rel=5e-8, abs=0) != actual
def test_dict_wrong_len(self):
assert {'a': 1, 'b': 2} != approx({'a': 1})
assert {'a': 1, 'b': 2} != approx({'a': 1, 'c': 2})
assert {'a': 1, 'b': 2} != approx({'a': 1, 'b': 2, 'c': 3})
def test_numpy_array(self):
try:
import numpy as np
except ImportError:
pytest.skip("numpy not installed")
actual = np.array([1 + 1e-7, 2 + 1e-8])
expected = np.array([1, 2])
# Return false if any element is outside the tolerance.
assert actual == approx(expected, rel=5e-7, abs=0)
assert actual != approx(expected, rel=5e-8, abs=0)
assert approx(expected, rel=5e-7, abs=0) == expected
assert approx(expected, rel=5e-8, abs=0) != actual
def test_numpy_array_wrong_shape(self):
try:
import numpy as np
except ImportError:
pytest.skip("numpy not installed")
import numpy as np
a12 = np.array([[1, 2]])
a21 = np.array([[1],[2]])
assert a12 != approx(a21)
assert a21 != approx(a12)
def test_non_number(self):
with pytest.raises(ValueError):
1 == approx("1")
with pytest.raises(ValueError):
"1" == approx(1)
def test_doctests(self):
parser = doctest.DocTestParser()